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Can anyone ID this zener?

Discussion in 'Datasheets, Manuals and Component Identification' started by Mongrel Shark, Nov 1, 2012.

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  1. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    So I got some Zenner diodes from a plasma tv. Some of them have numbers, which I have been able to look up. The others appear to have colored stripes, like a resistor? Is there a code or something I can look up? Maybe it's the same as resistor colours?


    Ive been doing some reading, and it seems a tester would be a good idea. I'm thinking a simple self blocking ossilater, capable of high voltage and as low amps as possible for safety.

    I can get 250v from 1-2v no worries, would that be enough?

    Here is a photo of the diodes in question. I think they are Zenners, because the pcb was marked ZD next to them. as opposed to just D

    [​IMG]

    Sorry i cant zoom in more, my macro mode is a bit average.

    I still have some on the PCB if a photo of that will help?
     

    Attached Files:

  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Jan 21, 2010
    What you need is a source of reasonably high voltage at a low current. couple of 9V batteries in series should be fine (even flat ones). Use this and a series resistor of (say) 10k and connect it to the zener.

    Use your multimeter to measure the voltage across the diode.

    One way around it will be around 0.6V, the other it will either be the battery voltage, or some lesser breakdown voltage of the diode.

    The voltage you read will be the approximate breakdown voltage off the diode (as long as it is less than the open circuit voltage).

    edit: yes, you can use a blocking oscillator to create the voltage, but rectify it and filter it, and use a series resistor.

    edit2: yes the bands do have some meaning, but they're not consistent. Here is one datasheet, but it doesn't contain the combination of colours you see here. Following the pattern these would be 62V zeners, but I'm not confident about that.

    edit3: Here is another resource. The coloured bands are a bit like codes on other surface mount devices, every manufacturer has their own convention.
     
    Last edited: Nov 1, 2012
  3. CocaCola

    CocaCola

    3,635
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    Apr 7, 2012
    Rohm does the color bands like that on their zeners, but I can't find a 'orange purple green' in any of the series that I looked over...

    *** As I walked away to do something Steve jumped in front :)
     
  4. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    What a pain. I'll just make a tester. I was hoping it would be something sensible. like resistor colors (as suggested by one site), which would make them 37 volts. There are also other colors on the board... red yellow green is another. Seem the only thing that's consistent is the green being the cathode...

    I found a few series lists with no orange purple either...

    Will find out in a bit... tester, once made will save me a lot of headaches. What sort of max volts do these things go to? Seems most of them are under 70v? Which means I can make a wireless tester :D If I need more than 70v I'll have to do it the old fashioned way. If they go higher, I will probably be needing some soon.... with all the HV stuff I'm looking into. I'll be running from 1v into the oscillator, from flat AA's Unless I want more than about 150v, then I need 2v in... so amps wont be a problem... I got the rectifying and smoothing sorted too :) just need to know a good max voltage.
     
  5. Mongrel Shark

    Mongrel Shark

    260
    18
    Jun 6, 2012
    Its a Samsung circuit board from a Samsung tv if that helps?
     
  6. Mongrel Shark

    Mongrel Shark

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    18
    Jun 6, 2012
    Found some sheets with the right colours, using google search refinment. In this case I added "dittos" to the bits the search must contain in that precice order
    So I typed zenner color "orange violet green" and got this result. http://tinyurl.com/bgt6jyr

    I'm tired of staring at data sheets though. off to make a tester..
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    It doesn't matter much what voltage you have. Just pick a resistor that will limit the current into a short circuit to maybe a mA or so (so about 1k/volt)

    At lower currents (say 100uA) you can use it to measure the breakdown voltage of all sorts of things with relative safety.
     
  8. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    Cool. So I will make it with a wide range of attachment too. I was going to put a pot on both sides of the test component. One to adjust voltage from the cap, the other to limit current once voltage is set.. I'll also use the lowest farad cap I can to smooth the voltage, that way it will be hard to pull a lot of amps from it..Sound good?
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    No need to adjust the voltage. A variable current limit is OK, but possibly overkill for version 1.

    The size of the capacitor needs to be low enough to charge relatively quickly. You might be able to get away with 10uF or so.

    Also, a small capacitor won't bite so hard if you put your fingers across it.
     
  10. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    Yes, you are correct. I wasn't thinking. The zenner will break over at the voltage... If I use my scope (a pain, I'll still do it the way you suggest) I could just put the zenner on the output of the oscillator and measure the peak on the Colector... it's not going to peak over the zenner voltage.

    Without a scope, the cap will only fill to the zenner voltage and a reading could be taken from the cap. Wish I had a plain volt meter... I might get one next shopping expedition... This project could make a great how to video. I need to take a break from SWES. It's messing with my head too much.

    I was thinking I might get away with smaller. I used a 1.08µf (hold alt and pres 230 on num pad then release alt for a µ :D) on the 250v from 2v version. It filled up in an instant. I was going to try .47µf first then go up a step at a time if it doesn't work...
     
  11. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,497
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    Jan 21, 2010
    yep, that will work.

    With a scope and an AC signal you could even have a go at plotting the curve of the zener. (interesting, but probably not overly useful).

    Don't you have a multimeter at all? Even the cheapest $10 multimeter is probably better than far more expensive analog meters used to be. I have two that cost under $20 and I use them all the time...
     
  12. Mongrel Shark

    Mongrel Shark

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    Jun 6, 2012
    Lol yes I have 5 DMM's and plan on getting (or making, good learner project) 2 more analog soon. Of the 5 I have (and yes I do use all 5 at once, for efficiency testing, 2 in 2 out and a spare) one is 15+years old (crap make that 20, I got it when I was in grade 5 which would be exactly 20 years last month, after my analog got destroyed by the school bully who tried to measure the resistance of a 240 outlet), 4 are fairly new. One was $30 and has a lux db and other environment sensors. as well as all the regular stuff. one was $5 and is exactly the same as the old one. It is one of my favorites, and I'm not afraid to kill it either for $5... Big box of them at my local electronics store. another was $50 and is the only DMM I have with induction meter, although I do have 3 dedicated induction meters too (yep I like to measure stuff:D) The flash one was $200, but it has trms in AC+DC huge cap range great display and a wireless usb thingy for the data-logger software that came with it. Its also IP67, so I can measure stuff a meter under water in a dust storm. Not that I can think why I would be that stupid. Never know though. I do have some "inspired moments"

    I also have a shoe box of test leads, as I have an addiction to buying clip and hook on ones from ebay. I think I have even had 5 meters and 2 channels of scope on a simple blocking oscillator. :D


    I'm tempted to do the scope thing too now you mention curve plotting. Did I mention I like to measure stuff. Some of my video audience could benefit from a good old fashioned graph plotting lesson too.
    Half of them have data logger DMM's and still get charge discharge curves all messed up... If only there was another 90 hours in each day...
     
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